Simon Gitter

Blockade of 5-hydroxytryptamine receptors in the central nervous system by β-adrenoceptor antagonists

Abstract (±)-propranolol, oxprenolol and pindolol in doses ranging from 0.5 to 5 mg/kg antagonised the head twitch produced in mice by 5HTP. These doses had no effect on the pinna reflex. (+) propranolol was inactive. These β-adrenoceptor antagonists also prevented the induction of sleep in 5-day old chicks by 5HT. Their activities in the two tests were similar to their 5HT receptor blocking potencies in the rat fundus preparation. It is suggested that these β-adrenoceptor antagonists may block some 5HT receptors in the central nervous system.

Pharmacological activity of oriental hornet (Vespa orientalis) venom.

Abstract The pharmacological activity of Oriental hornet ( Vespa orientalis ) venom has been studied and some of its active substances characterized. The ld 50 (i.v.) of venom for albino mice was 2·5 mg per kg. The venom caused contraction of isolated smooth muscle preparations, bronchoconstriction in anesthetized guinea pigs and when injected intradermally into rats and rabbits increased the permeability of microcirculation vessels. After intra-arterial injection, the venom blocked the directly and indirectly induced single twitches of cat gastrocnemius-soleus and tibialis anterior muscles, but it did not affect nerve conduction. The venom possessed protease and hyaluronidase activities, released histamine from mast cells, caused hemolysis and was immunogenic when injected into rabbits. The following substances were found in the venom: histamine, acetylcholine, 5-hydroxytryptamine, kinin(s), adrenaline, noradrenaline and dopamine. It was postulated that the catecholamines present might prolong the local action of the venom and be responsible for its ‘blanching’ effect observed upon i.d. application.

Hyperactivity in rats following postnatal anoxia

A model of hyperactive rats was produced by exposing pups to severe anoxia within 24 h following birth. These rats demonstrated augmented motor activity in ambulation, sniffing and rearing activities in an open field. Activity was significantly increased at 10 days of age, maximal at 20-25 days and returned to normal values around 6 weeks of age.

Influence of hemorrhage on the QRS complex of the electrocardiogram

Abstract The removal of blood from anesthetized cats or dogs invariably produces an immediate reduction of the amplitude of the QRS complex, which can be restored to normal by reinjecting the blood. In the present study it was demonstrated that the QRS changes are directly related to the changes of the heart volume, viz., reduction of QRS amplitude after bleeding or after clamping of the inferior vena cava or increase after overfilling of the heart. Anoxia, changes of lung volume, or rotation of the heart had not contributed to the registered QRS changes.

A new probe for heterogeneity in muscarinic receptors: 2-methyl-spiro-(1, 3-dioxolane-4, 3')-quinuclidine.

The title compound (MSDQ) is a new muscarinic agonist related to 3-acetoxyquinuclidine (3-AcQ) but also of a highly rigid structure. In view of this, it may constitute a probe for the detection of heterogeneity among muscarinic receptors. Indeed, equipotent molar ratios (EPMR) for ACh, 3-AcQ and MSDQ were as follows: guinea pig ileum, 1 : 14 : 240; vasodepressor effect in the cat, 1 : 6 : 188. But EPMR for 3-AcQ and MSDQ as stimulants of the superior cervical ganglion in the cat were 1 : 1 and for the induction of tremors in mice, 9 : 5. No such subtle differences in receptor specificity were detected when the probe used was the 2, 2-diphenyl analogue (DiPSDQ) of MSDQ which was a powerful competitive antagonist in all systems, more potent than atropine, but with a CNS/PNS activity of 1.1 compared to 26 for atropine. In view of this, the use of potent antagonists as probes for muscarinic receptor heterogeneity is questionable.

The presence of insulin in and some effects of exogenous insulin on hymenoptera tissues and body fluids

Abstract o 1. Radioimmunoassay technique has revealed the presence of insulin in the tissues of various Hymenopteran insects, including the honeybee Apis mellifera , the Oriental hornet Vespa orientalis and several other Paleoarctic social wasps, the Mason bee Chalicodoma sicula , the cuckoo wasp Chrysis sp. and the weaver ant Polyrachis simplex . 2. Laboratory determinations carried out in vivo and in vitro on several insects have shown that bovine insulin injected into insect hemolymph or incubated together with the hemolymph causes a significant drop in the glucose level of the fluid.

Behavioral differences in the developing rat following postnatal anoxia or postnatally injected AF-64A, a cholinergic neurotoxin

Rat pups were submitted postnatally to one of two procedures: a 25-min exposure to 100% nitrogen or an i.c.v. bilateral injection of AF-64A, 2 nmol contained in 1-microliter saline. Throughout further development of either group, their performance in passive and active avoidance tests and in amphetamine-induced stereotype behavior was followed and compared. Both groups exhibited hyperactivity which persisted until 42 days of age in the anoxia group and beyond 120 days in the AF-64A group. Both groups were equally inferior to controls in the passive avoidance test, but only the anoxia group was inferior to controls in the active avoidance test. Amphetamine-induced stereotype behavior was much less pronounced in the anoxia group relative to AF-64A-treated rats or to controls. The results suggest that the lesion induced by the neurotoxin is more specific and less widespread than the one caused by anoxia.

Phospholipases A and B activities of the oriental hornet (Vespa Orientalis) venom and venom apparatus

Phospholipases A and B activities of the oriental hornet (Vespa orientalis) venom and venom apparatus. Toxicon15, 141–156, 1977.—Oriental hornet venom is a rich source of both phospholipase A (PhA) and phospholipase B (PhB) activities. This was shown by incubating venom with egg yolk or with pure lecithin and lysolecithin. Activity was measured by titrating liberated fatty acids and by phosphorus analyses of separated phospholipids from thin-layer chromatographic plates. Both lecithin and lysolecithin were rapidly hydrolyzed by venom at pH 4 and 8. With egg yolk as substrate, the optimum Ph activity was observed at pH 5 although considerable activity was observed from pH 3·5 to 9·5. In contrast purified substrates showed greater activity at an alkaline pH, whether assay was in the presence of collidine-acetate or Tris buffer or in the presence or absence of ether. Ether dramatically changed the optimal pH for Ph activity, with egg yolk as substrate, from acidic to alkaline. It is not known whether these PhA and PhB activities are dual activities of a single enzyme or activities of two separate enzymes. The venom has neither PhC nor lipase activities. PhA and PhB activities were observed not only in pure venom (V), but also in venom sacs (VS) where the venom is stored, in the acid (venom) glands (H+) where the venom is produced, and in the alkaline (Dufours) gland (OH−) whose function is unknown. The release of free fatty acids from egg yolk at pH 5 was in the ratios of 1 (V): 0·13 (VS): 0·04 (H+): 0·30 (OH−). Measurements of Ph activities in combinations of the above preparations showed that strong activators or inhibitors of the enzyme are not present. The mid-gut, fat body and hemolymph of the hornet showed Ph activity only equal to about one-half of one per cent of that of the OH− gland. Antisera produced against V, VS, H+ and OH− were cross-reactive and inhibited to varying degrees the Ph activities of each of the above preparations. The highest titre antisera were produced in rabbits injected with V or VS, in contrast to the low titres produced with H+ and OH− glands. Low Ph activity is detectable in the venom sacs 2 days prior to emergence, with 20-fold higher activities being observed at 5 days of age. The oriental hornet may be extremely useful as a rich source of not only PhA but also PhB activities. The effects of this latter enzyme on biological systems have not been thoroughly evaluated. The drastic disruption of phospholipid structure and hydrophobic binding forces between phospholipid and protein, by the combined PhA plus PhB activities, may be responsible for some of the pharmacological actions of hornet venom.

Catecholamines in social wasps

Abstract 1. 1. Various tissues originating from several species of social wasps showed significant amounts of catecholamines (noradrenaline, adrenaline, dopamine and 5-hydroxytryptamine). 2. 2. Dopamine proved to be the most abundant among the catecholamines examined. 3. 3. The data are discussed in regard to possible functions of catecholamines in wasps.

Rhythms in acoustical communication by the oriental hornet, vespa orientalis

Abstract By analysis of the acoustical spectrum within the nest of the oriental hornet, three distinct and characteristic categories of sounds have been recognized: (a) Hunger signals produced by the hungry larvae through the scraping of their mandibles against the comb cell walls; (b) sounds which the workers, arranged in a ‘resting circle’ around the queen, produce by tapping their abdomens on the surfaces of the cells. These sounds are temporarily designated as ‘the taps of workers facing the queen’; and (c) additional worker sounds, also produced as in (b) but of a different rhythm, which have been designated in earlier publications as the ‘awakening taps of workers’ (Ishay & Schwartz 1965; Schaudeinischley & Ishay 1968; Ishay & Landau 1972; Ishay & Schwartz 1973). The particular ‘beat’ (spcificity) of each of the three sound groups has been investigated in an attempt to understand the significance of rhythms as a means of communication among hornets.